As a conventional electronic component, a multilayer chip inductor disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 5-57817 is known. The multilayer chip inductor disclosed in Japanese Utility Model Laid-Open Publication No. 5-57817 will be described below. FIG. 8 is an exploded oblique view of the multilayer chip inductor 500 disclosed in Japanese Utility Model Laid-Open Publication No. 5-57817.
The multilayer chip inductor 500 is formed by laminating a plurality of pieces of rectangular ferrite green sheets 501, and forming coil patterns 503 on some of the ferrite green sheets 501. Note that the coil patterns 503 are connected by through-hole conductors, and connected at the start and the end to external electrodes.
In the multilayer chip inductor 500, to reduce electrical resistance of the coil patterns 503, two pieces of ferrite green sheets 501 with the coil patterns 503 of the same shape formed thereon are stacked at a time, and the ends of the coil patterns 503 of the same shape are connected in parallel by the through-hole conductors, as shown in FIG. 8. That is, the multilayer chip inductor 500 is a multilayer chip inductor of a so-called multiturn type.
Incidentally, some of the coil patterns 503 of the multilayer chip inductor 500 are opposed and connected in a series to another coil pattern with one ferrite green sheet provided therebetween. For example, the coil patterns 503a and 503b shown in FIG. 8 are such coil patterns. Since the coil patterns 503a and 503b are connected in a series, there is a potential difference between a point P503a on the coil pattern 503a and a point P503b on the coil pattern 503b. Moreover, there is only one ferrite green sheet between the points P503a and P503b, and the points P503a and P503b overlap each other when they are viewed in a plan view in the direction of lamination. That is, the points P503a and P503b are located in proximity. In addition, since the multilayer chip inductor is of a multiturn type, typically, a relatively large current of 1 ampere [A] or more is assumed to flow therethrough. For the above reasons, the multilayer chip inductor 500 is susceptible to migration of silver or suchlike used in the coil patterns 503 between the points P503a and P503b (hereinafter, such a phenomenon will also be referred to as “metal migration”). As a result, the multilayer chip inductor 500 is susceptible to short-circuiting, so that the allowable ampacity of the multilayer chip inductor 500 is limited.